1. Field of the Invention
The present invention relates to a transportation system of floated carrier type and, more particularly, to a transportation system of floated carrier type which makes it possible to achieve savings in energy and space.
2. Discussion of Background
Recently, as a part of office automation and factory automation, it is being widely put into practice to transport items such as slips, documents, cash, and reference materials by means of a transporting system among a plurality of spots within a building.
A transporting system to be used for such purposes must move items to be transported fast and quietly. For this reason, in a transporting system of this kind the carrier is supported on guide rails without making contact with the guide rails. In order to support a carrier without making contact with guide rails air or magnetism is generally used to support the carrier. Of these, the magnetic support system may be regarded to be more promising, in view of reduced noise and its excellent followability of the guide rails.
The conventional transporting system of the magnetically floated type is a system for supporting the carrier by means of electromagnets in which the carrier is supported stably through control of the exciting current to the electromagnet. Accordingly, it is necessary to keep the coil of the electromagnet energized at all times which leads to the inevitable drawback that large amounts of electric power are consumed. With this in mind, there has been considered a system in which a majority of the magnetomotive force required for the electromagnets is supplied by permanent magnets in order to reduce the power consumed. Even in such a case, however, when an external force is applied to the carrier, by placing cargo on board the carrier, for instance, it becomes necessary to provide a force through electromagnets to push the carrier to its normal position. Therefore, an increase in the consumed power in this situation also becomes a matter of concern. Moreover, when increased electric power consumption is required for energizing the electromagnets, due to application of external forces to the carrier, it becomes necessary to use a power source with large enough capacity, which disadvantageously leads to a large scale system.